Abstract
Recently, thermoinduced magnetization (TiM) has been predicted to lead to
ferromagnetic properties in nanoparticles of antiferromagnetic materials
below the ordering temperature. Specifically, the susceptibility is found to
increase linearly as the temperature is increased. Here the magnetic
properties of linear chains of three-dimensional classical Heisenberg spins
are calculated both analytically and using Monte Carlo techniques. TiM is shown to
be associated with the ordering of the spins induced by a single-site
uniaxial anisotropy, and the per-spin susceptibility is found to be
approximately independent
of the number of spins in the chain. For large anisotropies, TiM is shown
analytically to be associated with the thermal fluctuations of individual spins,
in contrast to current theories.